Cartridge



or cartridge for the powder charge.

Patented Nov. 14, 1944 CARTRIDGE Arthur L. Yarbrough, Fullerton, Oallf.,asslgnor to Vera E. Yarbrough, Fullerton, Calif.

Application February 10, 1941, Serial No 378,255

13 Claims.

This invention relates generally to cartridges, and particularly tocartridges employing a comparatively large powder charge and whichdevelop relatively high explosive pressure, such as casing perforatinggun cartridges, or cartridges for high velocity or large rifles.

It is common practice in the casing perforating gun art to Provide acardboard or paper container Such a cartridge, however, is no more thana mere container, and has no inherent strength such as would enable itto withstand the high hydrostatic fluid pressures existing deep in awell. Accordingly, the openings of the gun which lead to the chambercontaining such a cartridge must be provided with fluid tight seals.This is a disadvantage and attempts have been made to provide apractical cartridge with metal walls of suflicient strength and rigidityto withstand the high fluid pressures in the casing. A cartridge of thiskind would also have the advantage. of protecting the cartridge chamberfrom burning by the powder. However, these efforts have met withfailure, owing to the fact that the explosive pressure developed in thecartridge is extremely high, and the result of the explosion is toexpand the metal side .walls of the cartridge very tightly against thechamber wall, in fact to more or less embed them into the chambersurface. The result is that the task of extracting the cartridgefollowing firing is exceedingly diflicult.

A similar situation exists with relatively high velocity or largecaliber rifie cartridges. Large caliber machine guns, for instance, arefrequently stopped by the sticking of an expanded cartridge in thebreech.

The general object of the present invention is accordingly to provide arigid or metal cartridge of such a nature as to be incapable of becomingexpansively bound in the cartridge chamber.

In accordance with the invention there is pro vided a cartridge having arigid but frangible side wall, which will be shattered or mutilated bythe explosion pressure in such a way'as will prevent binding within thechamber. The term frangible as herein defined denotes capability forbeing completely shattered, or shattered or runtured in part, or sodeformed, mutilated or weakened as to be incapable of becoming bound.within the firing chamber. For the purpose of a cartridge for a casingperforating gun, the walls are preferably made of sumcient strength towithstand the extreme hydrostatic fluid pressures existent deep down inwell casing, though of course the present invention is not necessarilylimited in application to situations in which the cartridge is actuallysubjected to external fluid pressure. And in the specific field ofcasing perforating guns, the cartridge of the present invention is ofadvantage even if the pressure fluid be independently sealed out, inthat it greatly protects the cartridge chamber against burning by thedirect effects of the explosion, while at the same time the easyremovability of the cartridge following firing is assured. In the caseof a cartridge for a rifle, there is of course no high hydrostatic fluidpressure to contend with, and the walls of the cartridge hence need nothave the same thickness and inherent strength as in the casingperforating gun cartridge.

The invention will be .best understood from the following detaileddescription of certain selected illustrative embodiments thereof,reference for this purpose being had to the accompanying drawing, inwhich:

Fig. 1 is a longitudinal medial section of an illustrative cartridge inaccordance with the invention mounted in a conventional type of casingperforating gun barrel;

Fig. la shows the cartridge of Fig. 1 after firins;

Fig. 2 is a longitudinal medial section through armodified form ofcartridge in accordance with the invention;

Fig. 3 is a transverse section on line 33 of Fig. 2;

Fig. 3a is a view similar to Fig. 3, but showing the results ofdischarging the cartridge;

Fig. 4 is a view similar to Fig. 2 but showing another modification;

Fig. 5 is an elevation of a cartridge in accordance with the inventiondesigned for a rifle, machine gun or the like; and

Fig. 6 is a section taken on line B-6 of Fig. 5.

In Fig. 1 numeral I0 designates generally a chamber block ofconventional type for a perforating gun, formed in one end with aninternally screwthreaded socket l I into which is threaded a barrel I2containing a shooting bore I3, the barrel l2 being set up against theshoulder at Ma. In back of socket II is a cylindrical cartridge chamberl4, of a diameter less than no part of the present invention. Any othersuitable barrel and chamber structure may be utilized.

An illustrative form of cartridge in accordance with the presentinvention comprises a cartridge shell designated generally at IS in Fig.1, being shown as positioned in the cartridge chamber l4 of chamberblock III, as illustrated. In the illustrative form of Fig. 1, thecartridge shell comprises a front end wall or head and an integrallyformed cylindricalv side wall or skirt 2|, made up of som suitablefrangible material, such for instance as cast iron, adapted to beshatteredor cracked by the force of the explosion occurring inside thecartridge shell. Head 20 and skirt 2| are of suflicient thickness towithstand comparatively high external hydrostatic fluid pressure, sothat if sealing means between the barrel and chamber block are notprovided, the cartridge will not be subject to crushing.

- That is to say, the cylindrical shell made up of head 20 and sidewalls 2| is a rigid member, not subject to crushing in the event ofexposure to the external hydrostatic fluid pressure, either in the eventof leakage past any fluid sealing means that may be provided, or in theevent of nonprovision of fluid sealing means. In this sense the shell isto be distinguished from an ordinary easily deformable paper, cardboardor fibre shell such as has heretofore been in common use, but which isentirely incapable of withstanding exter nal hydrostatic fluid pressure.

Various types of rear end closures for the cartridge may be provided. Ihere illustrate one suitable form of rear end closure comprising a plug24 having a cylindrical portion adapted to fit within the cartridgeShell I6 and a flange 25. Interpose'd between the plug 24 and the skirt2| of the cartridge shell l6, and between the flange 25 and theextremities of said skirt 2|, is a sealing and insulating washer orgasket 26 which both electrically separates the plug 24 and cartridgeshell i6 and forms a fluid-tight seal. The flange 25 is smaller than thediameter of the socket 'or chamber M, as well asthe outside diameter ofthe cartridge shell I6, so that when centered in the chamber l4 by thecartridge shell its periphery is not in electrical contact with the sidewalls of the chamber. Plug 24 is here shown as provided with an axialsocket 30 adapted to receive an electrically fired fuse 3|. Anelectrical conductor 32 soldered to plug 24 and passing out through therearward end of block it via passageway i5 conducts current to theinsulated plug, the current passing through the plug to the fuse. Thisfuse may typically and preferably be of a match-head type, such asmanufactured by the Atlas Powder Company, and projects a flame from itsforward end when heated by passage of an electrical current. Such fuses,are known and will require no detailed description herein. As stated,the fuse is provided with one electrical connection consisting of theabove mentioned conductor 32. The circuit is completed to ground via asecond conductor 35 which may be grounded to the inside of side wall 2|.While shell l6 contacts blocks l0, plug 24 is maintained out ofelectrical contact therewith by the provision of an insulation washer 36at the inner end of chamber l4 as well as the space afforded between theflange 25 and the side walls of the chamber l4.

A usual projectile 38 is positioned in bore I; in contact with cartridgehead 20. Projectile 38 may be fastened to or integral with cartridgehead 20, or it may simply be positioned against it. The cartridgecontains the usual charge of -explosive, as indicated at 39.

rupturing pressure is reached, a plug is sheared out of head 20 and theplug and projectile 38 are propelled from the shooting bore. The forceof the xplosion cracks, fractures or shatters the cylindrical wall 2| ofthe cartridge, and places it in such a condition that it can be readilyextracted from chamber H. To promote fracture by expansion andsubsequent looseness the cartridge originally may have a, slightlooseness of cylindric fit in the chamber. Fig. la shows the conditionof the cartridge after firing, a hole 40, of approximately the diameterof shooting bore l3, having been punched in its forward end, and thewall 2| being cracked from end to end. The fractured cartridge is looseinside chamber l4, and it is only necessary to remove barrel l2 and thento engage the cartridge underneath the shoulder left at 4| with anysuitable hooked tool in order to draw it forth.

Figs. 2, 3 and 3a show a modification, in which the frangibilitycharacteristics of the cartridge result from the provision of a seriesof scores, pref-' erably running longitudinally of the cartridge. Thecartridge again comprises, preferably, a head and integral cylindricalside wall, designated in this instance by numerals 20a and 2 la,respectively, and a rear end closure plug 34, the latter being typicallythe same as described in connection with Fig. 1. Head 20a and side wall2|a may in this instance be made up typically of steel, and side wall2|a is provided with a plurality of longitudinally extending grooves 50sunk in its outer surface. Insofar as frangibility characteristics areconcerned, these longitudinal grooves 50 may or may not extend the fulllength of the cartridge, though they are here shown terminating somewhatshort of the head end of the cartridge. Head 20a is again of course ofsuch a thickness dimen-- sion as will permit rupturing upon developmentof the desired explosive force inside the cartridge. As this explosionoccurs, the metalbetween the bottoms of the grooves 50 and the insideperipheral surface of wall 2 la is ruptured, as indicated in Fig. 3a.The explosive gases discharging through the longitudinal slots thusformed in side wall 2|a tend to equalize the pressures inside andoutside the cartridge, and thus the expansion of the cartridge andresulting binding is greatly reduced. Moreover, and probably still moreimportant, the longitudinal slots thus formed in the side wall of thecartridge weaken it to such an extent that it is entirely incapable ofexerting any substantial degree of outward force on the wall surfaces ofthe cartridge chamber. Thus in this form of the invention, the side wallof the cartridge is provided with longitudinally extending frangibleportions, which are completely ruptured or blown out as the explosionoccurs, leaving the cartridge in such a condition that it can be veryreadily extracted.

In this form of cartridge the thickness of the cylindric wall at thescores is suflicient to withstand the external hydrostatic pressures,but insuflicient to withstand the internal explosive pressures. And thisform of cartridge may also have a slight cylindric looseness of fit inthe chamber,

Figs. and 6 show the invention embodied as a rifle cartridge,- numeral60 designating a metal cartridge shell having the usual closure or head60a, and numeral 6| designating the projectile fitted in its end. Shell60 is formed throughout the major portion of its length withlongitudinal grooves 62. It may also have some looseness of fit withinthe cartridge chamber or breech. When the cartridge is fired, the metalbetween the inner surface of the shell and the bottoms of these groovesis ruptured the same as in the case of the casing perforating guncartridge of the types of Figs. 2 to 4, thereby weakening the shell ordestroying its rigidity to such an extent that there is completeassurance against binding within the breech of the gun.

It will now be understood that I have provided a cartridge having afrangible side wall, or frangible (weakened) side wall parts, such thatwhen the cartridge is fired, the resulting explosive force fractures orruptures the side wall of the shell, or parts of it, with the resultthat the rigidity and form of the cartridge are reduced and changed tosuch an extent and in such a way that expansive binding of the cartridgewithin the cartridge chamber is made impossible.

I have now shown for illustrative purposes several typical embodimentsof my invention; it will be understood, however, that these are forillustrative purposes, and that various changes in design, structure andarrangement may be made without departing from the spirit and scope ofthe invention or of the appended claims.

I claim:

1. A gun cartridge for guns havin a gun bore and a powder chamber oflarger diameter than the gun bore, comprising: a single piece cupshapedshell having a closed end covering the gun bore and a skirt portionextending substantially the length of the powder chamber, and restrainedthereby against endwise displacement; and an explosive resistant cap forthe open end of said shell to form therewith a compartment for anexplosive, the skirt of said shell having at least a longitudinallyextending portion of its periphery spaced from the walls of saidchamber, said portion being incapable of withstanding the explosivepressure generated in said shell and adapted to rupture longitudinallywithin the area defined by said portion and the opposing chamber wallsupon expansion of said shell into contact with said chamber walls underurge of said explosive.

2. A cartridge for guns having a gun bore and a cylindrical powderchamber larger in diameter than the gun bore, comprising: a metallicshell adapted to contain an explosive charge and having an end portioncovering said gun bore and an integral skirt portion extendingsubstantially the length of said powder chamber, said skirt definingwith said chamber a clearance area extending substantially the length ofsaid skirt and occupying at least a portion of its periphery, theportion of said skirt defining said clearance area adapted, whenexpanded radially therein under urge of explosive pressures, to exceedits yield point and therefore rupture, splitting the skirt longitudinally.

3. A cartridge construction, as set forth in claim 2, which includes: abullet secured to said end portion and extending therefrom into said gunbore, and said end portion adapted to restrain said bullet until thepressure within said powder chamber has risen to a predetermined value.

4. The combination with a gun perforator having a cylindrical cartridgechamber, a screwthreaded barrel socket of larger diameter than saidchamber and extending therefrom, and a barrel fitting said socket andhaving a gun bore smaller than said chamber, of a cartridge unitcomprising: a cup-shaped metallic shell having a rupturable end portioncovering said gun bore, and a skirt portion extending substantially thelength of said cartridge chamber;- the skirt portion of said shelldefining with the cylindrical walls of said cartridge chamber an annularclearance space sufiiciently great that said shell rupturessubstantially completely on expanding into contact with said chamberwalls under urge of an explosive charge in said shell, the juncture ofthe skirt and end of said shell forming an explosive resistant means forconfining the pressure area against said gun barrel to the area of saidcartridge chamber.

5. A cartridge construction, as set forth in claim 4, which includes: abullet secured to said rupturable end portion and extending into saidgun bore, said end portion adapted to restrain the bullet until theexplosive pressure in said cartridge exceeds a predetermined value.

6. The combination with a gun perforator having a cartridge chamber, anelectrical contact in the rear end of said cartridge chamber and a gunbore extending from the outer end thereof, of a cartridge comprising: acup-shaped metallic shell having an end portion covering said gun bore,and a skirt portion extending toward the rear end of said chamber; apressure resistant contact block engageable with and bridging saidelectrical contact, said contact block closing the open end of saidshell, said contact block being electrically isolated from saidcartridge chamber and said shell; an explosive charge and electricaligniter in said shell; said cartridge adapted to fit in said cartridgechamber with said contact block supported against explosive pressures bythe rear end of said cartridge chamber, the skirt of said shell havingat least a portion of its periphery along its length spaced from thewalls of said chamber, said portion being incapable of withstanding theexplosive pressures generated in said shell, and adapted to rupturelongitudinally within the area defined by said portion when expandedunder urge of said explosive charge.

7. A cartridge construction, as set forth in claim 6, wherein said shelland contact block form a liquid-tight closure capable of withstandingthe hydrostatic pressure of liquid when the gun perforator is submergedin the liquid contained in a well bore.

8. A cartridge construction, as set forth in claim 6, wherein the endportion of said shell covering said gun bore is adapted to be rupturedwhen the explosive pressure in said cartridge exceeds a predeterminedpressure; and a bullet attached to said end portion.

9. The combination with a gun perforator adapted to be submerged togreat depths in liquids contained in a well bore, and having a cartridgechamber and a gun bore extending therefrom of a cartridge unitcomprising: a fluid-tight metallic case containing an explosive chargeand adapted to withstand the external hydrostatic pressure of wellfluids in which the gun perforator is immersed, and fitting loosely insaid cartridge chamber, portions of said case defining with the walls orsaid cartridge chamber a clearance space of sufficient area that saidportions rupture upon expansion of said case under urge of saidexplosive charge; and a bullet extending from said case into said gunbarrel.

10. The combination with a gun perforator adapted to be submerged togreat depths in liquids contained in a well bore, and having a cartridgechamber and a gun bore extending therefrom, of a cartridge unitcomprising: a fluidtight metallic case containing an explosive chargeand adapted to withstand the external hydrostatic pressure of wellfluids in which the gun perforator is immersed, at least portions ofsaid case defining with the walls of said cartridge chamber a clearancespace of suflicient longitudinal and radial extent that said portionsrupture upon expansion of said case under urge of said explosive charge;a bullet extending from said case into said gun barrel; means includinga fluid, seal for making electrical connection from said gun perforatorinto said case; and an electrical igniter in said case.

11. The combination with a gun perforator adapted to be submerged togreat depths in liquids contained in a well bore, and having a cartridgechamber, an electrical contact at the base end of said cartridgechamber, and a gun bore extending from the outer end, of a cartridgecomchamber a clearance space of sufficient area that said portionsrupture upon expansion of said case under urge of said explosive charge;a bullet extending from said case into said gun barrel; an electriccontact incorporated in said case and engageable with the electriccontact of said gun perforator; a fluid seal means for the junction ofsaid contacts; and an electrical igniter in said case.

12. A construction, as set forth in claim 9, wherein a portion of saidcase covers said gun bore and is adapted to give way when the explosivepressure in said case exceeds a predetermined value, and a bullet isattached to said portion and extends into said gun bore.

13. A construction, as set forth in claim 11, wherein a portion of saidcase covers said gun bore and is adapted to give way when the explosivepressure in said case exceeds a predetermined value, and a bullet isattached to said portion and extends into said gun bore.

ARTHUR L. YARBROUGH.

